from math import sqrt
def getNum():
    nums = []
    iNumStr = input("请输入数字:")
    while iNumStr !="":
        nums.append(eval(iNumStr))
        iNumStr = input("请输入数字:")
    return nums
def mean(numbers):
    s = 0.0
    for num in numbers:
        s = s + num
    return s / len(numbers)
def dev(numbers,mean):
    sdev = 0.0
    for num in numbers:
        sdev = sdev + (num - mean)**2
    return sqrt(sdev / (len(numbers)-1))
def median(numbers):
    new = sorted(numbers)
    size = len(numbers)
    if size % 2 == 0:
        med = (new[size//2-1] + new[size//2])/2
    else:
        med = new[size//2]
    return med
n = getNum()
m = mean(n)
print("平均值:{},标准差{:.2},中位数:{}.".format(m,dev(n,m),median(n)))
